C# (.Net) Open Excel Template and Create Font,Border,Color,Style (Office 2003,2007,2010)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using Excel = Microsoft.Office.Interop.Excel; 

namespace ExcelC
{
    public partial class frmExcel : Form
    {
        public frmExcel()
        {
            InitializeComponent();
        }

        private void btnExcel_Click(object sender, EventArgs e)
        {
            Excel.Application xlApp;
            Excel.Workbook xlWorkBook;
            Excel.Worksheet xlWorkSheet;
            object mis = Type.Missing;
            string strTemplate = "C:\\ExcelC\\Xls\\Template.xls";
            string strFileName = "C:\\ExcelC\\Xls\\GenExcel.xls";

            xlApp = new Excel.ApplicationClass();
            //xlApp = new Excel.Application();
            xlWorkBook = xlApp.Workbooks.Open(strTemplate, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
                 
            xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
            xlWorkSheet.Name = "My Sheet";
            
            xlWorkSheet.Cells[2, 1] = "DataCol 1";
            xlWorkSheet.Cells[2, 2] = "DataCol 2";
            xlWorkSheet.Cells[2, 3] = "DataCol 3";
            xlWorkSheet.Cells[2, 4] = "DataCol 4";
            xlWorkSheet.Cells[2, 5] = "DataCol 5";
            xlWorkSheet.Cells[2, 6] = "DataCol 6";
            xlWorkSheet.Cells[2, 7] = "DataCol 7";
            xlWorkSheet.Cells[2, 8] = "DataCol 8";
            xlWorkSheet.Cells[2, 9] = "DataCol 9";

            xlWorkSheet.get_Range("A3", "I3").Merge(true);
            xlWorkSheet.get_Range("A3", "I3").BorderAround(Excel.XlLineStyle.xlContinuous, Excel.XlBorderWeight.xlMedium, Excel.XlColorIndex.xlColorIndexAutomatic, Excel.XlColorIndex.xlColorIndexAutomatic);
            xlWorkSheet.get_Range("A3", "I3").Font.Name = "Tahoma";
            xlWorkSheet.get_Range("A3", "I3").Font.Size = "15";
           // xlWorkSheet.get_Range("A3", "I3").HorizontalAlignment = 4;
            xlWorkSheet.get_Range("A3", "I3").VerticalAlignment = -4108;
            xlWorkSheet.get_Range("A3", "I3").HorizontalAlignment = -4108;
            xlWorkSheet.get_Range("A3", "I3").Interior.ColorIndex = 44;
            xlWorkSheet.get_Range("A3", "I3").Font.ColorIndex = 4;
            xlWorkSheet.get_Range("A3", "I3").Font.Italic = true;

            xlWorkSheet.Cells[3, 1] = "Hello Hello Hello Hello";

            xlWorkBook.SaveAs(strFileName,
                mis, mis, mis, mis, mis, Excel.XlSaveAsAccessMode.xlExclusive, mis, mis, mis, mis, mis);
            xlWorkBook.Close(true, mis, mis);
            xlApp.Quit();

            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorkBook);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorkSheet);

            xlApp = null;
            xlWorkBook = null;
            xlWorkSheet = null;
            GC.Collect();

            MessageBox.Show("Generate Successfully");

        }

    }
}